This a little piece Dan from VEG published recently in the New Zealand Permaculture Newsletter...
I had a soil-building revelation recently. It started with a course on holistic management. Holistic management is, in part, a way to build deep fertile soil faster and cheaper than anything else I’ve heard of. I found the idea challenging at first, coming from the perspective that:
1) Deforestation is one of our most pressing issues
2) The two worst enemies of reforesting our landscapes are grass and hard-hoofed grass-eaters like cows or sheep.
Like many environmentalists, I thought step one to a cleaner, greener planet was removing the livestock and step two was repressing the grass so the trees could come back. I have changed my mind. Holistic management helps farmers rotate livestock over grass where the grass builds soil fast. How does grass do this? Well, unlike a tree, which is based around a branching pattern, a blade of grass is like a straight, unwavering highway down which carbon flows thick and fast from the atmosphere into the soil. Where trees store carbon in their trucks, limbs and roots, grass stores carbon in the soil, feeding soil life and lifting soil carbon levels in a hurry. Add the manure and urine of the grazing livestock and you’ve got an unparalleled natural soil-building process. There are a few rules of the game, and one is that once hard-grazed for a short time, grasses require extended rest periods if soil is to be built rather than depleted over time. So the well-known problem with overgrazing is not from the animals that eat the grass, its from the animals that manage the animals that eat the grass – us!
So what are some implications of all this, and what use are these techniques in a backyard?
One implication is that when you’re starting from poor soil, you can potentially have healthier, larger trees in the long run if you hold off planting them for a year or two. During that year or two you can manage grasses to build soil carbon first. I’ve experienced this from implementation work in the Melbourne suburbs, where we often start with the poorest soil imaginable – grey powdery silt going down into grey-yellow clay. No crumb structure, no organic matter, and not a worm to be seen. Within a few years the results are clear to see - underneath a grassed and either mowed and/or grazed orchard the topsoil is much deeper and higher in organic matter and worms than in areas where grass is absent and there has only been compost and mulch.
This doesn’t mean the soil underneath your lawn will be amazing, as in most cases lawns aren’t given a sufficient rest period before being mowed again. This creates stunted root growth and hence soil development. Limited grass and weed diversity also restrict benefits for the soil. Unfortunately, there is an inverse correlation between what our culture considers a good-looking lawn and a soil-building grass polyculture.
A second implication is that if you have backyard chooks, ducks, geese, rabbits, or similar, you can use these in concert with grasses to build your soil fertility year on year. All you have to do is ensure that once the grass is grazed down you give it a good rest. An easy way to do this is to have more than one defined and gated run. The design in the picture below shows an example where chickens can be easily pulsed from one run to the next and back again.
Of course these techniques only work within a larger system including much else, but from now on I’ll have a lot more respect for the role of grasses in our landscapes, and their amazing potential to help us build soil for our edible gardens.